{
  "abstract": "Background Interstitial lung disease (ILD) is a major pulmonary complication of idiopathic inflammatory myopathy (IIM), where early diagnosis improves outcomes. While high-resolution CT (HRCT) remains the gold standard, its radiation exposure poses concerns. Serum Krebs von den Lungen-6 (KL-6) and lung ultrasound (LUS) B-lines offer non-invasive alternatives, though their optimal diagnostic cut-offs and combined utility for IIM-ILD remain undefined. This study aimed to establish these cut-offs, evaluate diagnostic performance and develop a clinical prediction model.Methods In this single-centre observational study, 162 patients diagnosed with IIM between 2020 and 2024 were enrolled. All underwent serum KL-6 testing, and 120 received systematic 50-point LUS examinations. Using HRCT as the reference standard for ILD diagnosis, receiver operating characteristics (ROC) curve analysis was used to determine optimal cut-offs and construct a combined nomogram.Results KL-6 levels were significantly elevated in the ILD group (n=113) compared with non-ILD (n=49). The optimal KL-6 cut-off was 553 U/mL (area under the curve (AUC)=0.895, sensitivity 69%, specificity 95.9%). For LUS B-lines number, 25 was recommended as the clinical threshold (sensitivity 98.8%). Their combination enhanced diagnostic performance (AUC=0.984). An online prediction model demonstrated strong clinical applicability. In an exploratory analysis of the rapid-progressive ILD subgroups, KL-6 and B-lines showed only modest predictive value (AUC ≈ 0.65).Conclusion KL-6 ≥553 U/mL and B-lines ≥25 are effective screening thresholds, with combined use significantly improving diagnostic accuracy. The prediction model provides a practical tool for early identification in similar clinical settings. To optimise and generalise its use, external validation in multicentre cohorts is warranted.",
  "authors": [
    {
      "affiliations": [
        "Department of Rheumatology and Immunology, Shantou Central Hospital, Shantou, China"
      ],
      "name": "Weijin Zhang"
    },
    {
      "affiliations": [
        "Department of Neurology, Shantou Central Hospital, Shantou, China"
      ],
      "name": "Qiongbing Zheng"
    },
    {
      "affiliations": [
        "Department of Rheumatology and Immunology, Shantou Central Hospital, Shantou, China"
      ],
      "name": "Shaoyu Zheng"
    },
    {
      "affiliations": [
        "Department of Radiology, Shantou Central Hospital, Shantou, China"
      ],
      "name": "Guangzhou Du"
    },
    {
      "affiliations": [
        "Department of Pulmonary and Critical Care Medicine, Shantou Central Hospital, Shantou, China"
      ],
      "name": "Qichuan Zhang"
    },
    {
      "affiliations": [
        "Department of Pulmonary and Critical Care Medicine, Shantou Central Hospital, Shantou, China"
      ],
      "name": "Shuhan Wu"
    },
    {
      "affiliations": [
        "Clinical Research Center, Shantou Central Hospital, Shantou, China"
      ],
      "name": "Guoxin Huang"
    },
    {
      "affiliations": [
        "Department of Rheumatology and Immunology, Shantou Central Hospital, Shantou, China"
      ],
      "name": "Zexuan Zhou"
    },
    {
      "affiliations": [
        "Department of Rheumatology and Immunology, Shantou Central Hospital, Shantou, China"
      ],
      "name": "Kedi Zheng"
    },
    {
      "affiliations": [
        "Department of Rheumatology and Immunology, Shantou Central Hospital, Shantou, China"
      ],
      "name": "Jianqun Lin"
    },
    {
      "affiliations": [
        "Department of Rheumatology and Immunology, Shantou Central Hospital, Shantou, China"
      ],
      "name": "Shijian Hu"
    },
    {
      "affiliations": [
        "Department of Rheumatology and Immunology, Shantou Central Hospital, Shantou, China"
      ],
      "name": "Qisheng Lin"
    },
    {
      "affiliations": [
        "Department of Rheumatology and Immunology, Shantou Central Hospital, Shantou, China"
      ],
      "name": "Jinghua Zhuang"
    },
    {
      "affiliations": [
        "Department of Ultrasound, The First Affiliated Hospital of Shantou University Medical College, Shantou, China"
      ],
      "name": "Qingzi Chen"
    },
    {
      "affiliations": [
        "Department of Pulmonology, Cattinara Hospital, University of Trieste, Trieste, Italy"
      ],
      "name": "Barbara Ruaro"
    },
    {
      "affiliations": [
        "Rheumatology Department, Oslo University Hospital, Oslo, Norway"
      ],
      "name": "Anna-Maria Hoffmann-Vold"
    },
    {
      "affiliations": [
        "Unit of Immunology, Rheumatology, Allergy and Rare Diseases, IRCCS San Raffaele, Milan, Italy",
        "Vita-Salute San Raffaele University, Milan, Italy",
        "Inflammation Fibrosis and Ageing Initiative (INFLAGE), Division of Genetics and Cell Biology, IRCCS San Raffaele Scientific Institute, Milan, Italy"
      ],
      "name": "Marco Matucci-Cerinic"
    },
    {
      "affiliations": [
        "Unit of Immunology, Rheumatology, Allergy and Rare Diseases, IRCCS San Raffaele, Milan, Italy",
        "Division of Rheumatology, Department of Medicine, University of California Los Angeles, Los Angeles, California, USA",
        "University of Washington, Seattle, Washington, USA"
      ],
      "name": "Daniel E Furst"
    },
    {
      "affiliations": [
        "Department of Ultrasound, The First Affiliated Hospital of Shantou University Medical College, Shantou, China"
      ],
      "name": "Shaoqi Chen"
    },
    {
      "affiliations": [
        "Department of Rheumatology and Immunology, Shantou Central Hospital, Shantou, China"
      ],
      "name": "Yukai Wang"
    }
  ],
  "title": "Serum KL-6 and lung ultrasound B-lines: a combined non-invasive model for screening and predicting interstitial lung disease in idiopathic inflammatory myopathy",
  "uid": "47a0cdcf-8a57-5d93-98ff-e533fc8dd674"
}